From: "Dave VanHorn"
Subject: Re: Designing a barcode reader
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Date: Sat, 28 Sep 2002 16:42:13 GMT
"Alan" wrote in message
> You maight take a look at:
> for a start
The basic approach is to start a timer running on the first edge you see,
then capture the value and reset the timer on each subsequent edge. If the
timer overflows, then the user is scanning too slowly, or has hit the end of
With all the timing data in ram, you start looking for a valid start char,
tossing noise as you go.
You'll have to work from both ends, since the scan could be in any
Once you have a start char, start stripping out the chars.
There's a lot of interesting things to compensate for, like pen distortion,
where black things look larger than white things, even when they are not.
I've posted complete code for a reader on avrfreaks, but it is UPC/EAN only.
Still, not a bad starting point.